Fluid pressure operated trip actuating mechanism



Aug. 15, 1950 B. s. FERGUSON 2,519,311

FLUID PRESSURE OPERATED TRIP ACTUATING MECHANISM 3 Sheets-Sheet 1 Filed July 21, 1945 y4,34 3. -35 F 're a 1m "55 i a r E i 5 m! in. F l1 I INVEN TOR. Berlin S. Ferguson ATTO YS ug- 15, 1950 B. s. FERGUSON 2,519,311

I? AC'ITUATING MECHANISM 3 Sheets-Sheet 2 FLUID PRESSURE OPERATED TR Filed July 21, 1945 INVENTOR Berlin S. Ferguson M4 I" ATTORN S 1950 B. s. FERGUSON FLUID PRESSURE OPERATED TRIP ACTUATING MECHANISM 5 Sheets-Sheet :5

Filed July 21, 19

1 w 7 5% mm nwm u v I NQ MQ wm l1. 1 f \7 mm m #9 R Q .NN Sn an INVENTOR. Berlin 5. Ferguso BY M4 7* k5? ATTORNE s Patented Aug. 15, 1950 2,519,311 FLUID PRESSURE OPERATED TRIP ACTUATING Berlin S. Ferguson,

The Byers Machine Application July 21,

to a fluid pressure trip operating mechanism and particularly to a mechanism suitable for releasing a holding latch such as the latch holding the bottom of a power shovel dipper in lock retaining position.

The invention has for an object to provide a rapidly operating air pressure actuated trip mechanism that is controlled by a simple hand operated valve and in which the air pressure delivered to the mechanism upon actuation of the valve is utilized to reset the mechanism upon the return of the valve to its closed position.

A further object of the invention is to provide a simple and compact pressure controlled valve mechanism for automatically reversing the movement of an actuating piston when the air pressure source is cut ofi from the cylinder.

An additional object is to provide a cylinder and piston trip mechanism that is controlled by a pressure operated valve that admits air under pressure to the cylinder and which controls the pressures acting upon the piston to return the piston to its normal position after the cylinder has been cut off from the fluid pressure supply.

Another object of the invention is to provide a trip operating mechanism of the piston and cylinder type in whichthe actuating pressure is controlled by a valve mechanism mounted in the piston rod.

With the above and other objects in View, the

the trip mech- This invention relates forth in the appended variations and modifications thereof as will be apparent to one skilled in the art to which the invention pertains.

Reference should be had to the accompanying drawings forming a part of this specification, in which: I

Figure l is a side elevation of a power shovel to which the invention is applied;

Fig. 2 is a fragmentary plan view, as viewed MECHANISM Ravenna, Ohio, assignor to Company, Ravenna, Ohio, a corporation of Ohio 1945, Serial No. 606,399

2 Claims. (Cl. 121-38) from the line indicated at 2'-'-2 in Fig. 'l, showing the pull cable that shovel latch;

Fig. 3 is a plan view ated trip mechanism boom, as viewed from in Fig. 1; I i

Fig. 4 is a fragmentary side elevation showing a portion of the air pressure supply pipe and connections therefrom to the pressure operated control valve;

Fig. 5 is a longitudinal section. onthe line in-' is utilized for releasing the of the air pressure operthat is mounted on the the line indicated at 3--3 dicated at 5-5 in Fig. 3, through the fluid pressure operated trip actuating mechanism;

Fig. 6 l is a longitudinal section showing the pressure operated valve in position to admit pressure to the cylinder;

Fig. 'I is an end elevation of the trip actuating mechanism viewed from the lower end as indicated at l--| in Fig. 5;

Fig. 8 is a section taken at 8-8 in Fig. 5; I

Fig. 9 is a plan view of a. trip actuating mechanism of modified construction;

Fig. 10 is a view showing the trip actuating mechanism partly in side elevation and partly in longitudinal vertical section;

Fig. 11 is a transverse section taken on the line indicated at ll--H in Fig. 10, and

Fig; 12 is a transverse section taken on the line on the line indicated indicated at I2-l2 in Fig. 10.

In the accompanying drawings the invention is shown applied to a power shovel *for releasing the hinged bottom l of a dipper or shovel 2 that is mounted upon a dipper stick 3. The dipper stick 3 is slidable in a yoke 4 that is pivoted to a boom 5 on a suitable carriage 6. The shovel 2 is raised or lowered by means of a suitable hoist line 1' and the dipper stick 3 is extended or retracted by means of actuating pinions 8 engaging racks on the dipper stick 3, the pinions 8 being attached to-a shaft 9 that is driven by suitable means such as a sprocket chain In. Adjacent one end thereof the shaft 9 has a drum ll attached thereto which has a diameter substantially twice the pitch diameter of the pinions 8. The bottom I is controlled by a trip line 12 that may be mounted as shown in my Patent 2,309,759, granted February 2, 1943. The cable I2 is attached at one end to the drum ll, runs over a sheave l3 mounted on the outer end of a lever [A that is pivotally connected to the dipper stick 3 and over a second sheave 15 that is rotatably mounted on the shaft 9 and extends toward the lower end of the boom. The lever I4 is connected by means of an actuating chain ll to the latch (not shown) which retains the bottom I in closed position.

'As the shaft 9 rotates to retract or extend the dipper stick 3, the drum l I winds up a length of cable l2 substantially equal to twice the linear movement of the dipper stick 3, so that the movement of the sheave [3 with respect to the drums II and I5 is compensated for and such movement will not cause either slack or tension in the cablel2. A pull exerted on the cable l2 and acting on the sheave l3 and lever M will exert a pull on the chain latch.

As herein shown, the cable I2 is attached to a fluid pressure actuating cylinder [8 slidably mounted on the boom 5 adjacent its lower end. The cylinder I 8 is supported by a frame composed of parallel angle bars I9 and a cross. member 20 connecting the lower ends of the angle bars [9. The bars l9 are bolted to the boom 5 and the cross member 20 supports a stationary piston 2! having a rod 22 that is attached adjacent its lower end to the member 20. At its upper endthe cylinder I8 has a head 23 to which the cable I 2 is attached and the head 23 is: connected by tie rods 24 to a head 25 at the lower end of the cylinder which is slidable upon the piston rod 22. The cylinder head 23 carries guide members 26 upon opposite sides thereof which have channels to receive ways 21 attached to the inner faces of the angle bars IS. The lower head 25 of the cylinder is connected to the cross member 20 bymeans of an extensible boot 28 which serves as a protective housing for the exposed portion of the piston rod 22 between the cylinder I8 and the cross member 20.

The piston rod .22 is of tubular form and serves as a casing through which fluid under pressure is delivered to the interior of the cylinder l8. A head 29- is attached to the lower end of the piston rod 22 and pipes 30 and 3| connect the head 29 with a pressure pipe 32. A control valve 33 is mounted in the pipe 3| and this valve is provided with a handle 34. The valve 33 serves to connect the head 29 with the pressure conduit 32 or to connect the head 29 to the atmosphere through a vent 35 in the casing of the valve 33. The valve 33 serves to control the operation of the trip mechanism, the pressure delivered through the pipe 3| past the valve 33 serving to operate a valve mechanism which controls the delivery of fluid under pressure through the pipe 30 to the cylinder l8, as will be hereinafter explained.

As shown in Figs. 5 and 6 of the drawings. the piston rod 22 has a reduced upper end portion 36 upon which the piston 2| comprising a body portion 31, sealing cups 38 and 39 and retaining rings- 40 and 4| is mounted. The piston is clamped against a shoulder 42 at the inner end of the reduced portion 36 so that an actuating pressure chamber for operating the trip mechanism is provided between the piston and the head 25; The piston rod 22 has an axial bore 43 which is closed at its upper end by a plug 44- which is secured in the bore of the piston rod by any suitable means such as by welding. The'plug- 44- has a projecting threaded portion 45 and beyond the threaded portion 45 the plug has a plunger 46 of cylindrical form and of less diameter than the threaded portion. A nut 41' on the threaded portion 45 serves to clamp a retaining collar 48 I! to trip the holding against the retaining ring 40 to clamp the pistonagainst the shoulder 42. The head 23 of the cylinder I8 is provided with a central cushioning chamber 49 to receive the plunger 46 as the cylinder approaches its lowermost position. The plunger 46 fits in the chamber 49 and traps a body of air in the chamber 49, and this trapped body of air provides an elastic cushion to cushion the impact of the cylinder head 23 against the. upper end of the piston rod.

A tubular valve member 50 is slidably mounted in the bore 43 of the piston rod and the valve; member 53 has a cylindrical head or piston portion 5| of slightly enlarged diameter thathas a sliding fit in a counterbore 52 at the lower end of the piston rod 22. A plug 53 is mounted in the lower end of the tubular valve member 50 and is secured to the valve member by any suitable means such as a locking pin 54. The plug 53 has a cylindrical extension 55 of slightly reduced diameter that is slidable in the head 29- attached to the lower end of the piston rod. The head 29 is provided with a chamber 55 that opens to the counterbore 52 in which the head 5! of the valve is slidably mounted. The head 29 also has a second chamber 51 adjacent its outer end to which the pipe 39 is connected. The projecting portion of the plug 53'extends through the chambers' 56 and 51 and sealing rings 58 and 59 are mounted in the chamber 51 to prevent leakage of air under pressure along the extension either inwardly or outwardly.

An axial passage 60 is provided in the plug 53 and the outer end of this passage is closed by a suitable plug 6L Lateral passages 62 connect the passage 60 with the chamber 5'! and a lateral opening 63 connects the passage 60 through the tubular valve 50 to a longitudinal passage 64 formed by a groove in the exterior surface of the valve- 50. A port 65 in the tubular piston rod 22 serves to connect the passage 64 with the pressure chamber in the cylinder l8 that surrounds the piston rod between the lower head 25 and the piston.

The valve 50' is normally held in a. position in which the port 65 is closed by means of a coil spring 65- that is interposed between the plug 44 and a spacer tube 61 that is interposed between the spring 65 and the plug 53 at the lower end of the valve member. When the valve 53 is moved from the position shown in Fig. 5 to the position shown in Fig. 6, the passage 64 is brought into communication with the port 65 and air under pressure is delivered from the pressure pipe 32 through the pipe 30, the chamber 51' and passages 60 and 64 to the pressure chamber of the cylinder [-8. The spring 66 normally holds the valve 50 in closed position as shown in Fig. 5, but whenever air under'pressure is delivered to the chamber 56 by actuation of the valve 33, the valve 50 is shifted to connect the port 65 with the pressure conduit through the chamber 51 and passages 60 and 64 to actuate the cylinder.

A passage 68 in the plug 44 establishes communication between the interior of the tubular valve member 50 and the upper chamber of the cylinder [8. A circumferential groove 69; is providedin the valve member 50 adjacent its lower end and this groove communicates with a passage 10 to the interior of the hollow valve 50L An exhaustfportTI inthe tubular piston rod 22'registors in one position of the valve 50 with the groove 69 to permit air to escape from the interiorof the valveand the upper chamber of the cylinder to the atmosphere;

Adjacent its upper end. the piston rod 22 has a second port 12. that opens into. the annular pressure chamber of the cylinder between the port 65 and the shoulder 42. A groove 13 in the valve 5!]v registers with the port 12 when the valve 50 is in the position shown in Fig; 5, and the groove 7.3 is connected: to the interior of the valve 50' through radial openings 14.

The annular space; around thepiston rod 22 between thelower head 25 oi. the cylinder i8 and the piston forms the main pressure chamber ofthe cylinder to which pressure is admitted tor impart. thev trip operating; stroke to the. cylinder.

The space between the piston and the upper head When the valve 33 is positioned as shown in 1 Fig. 4 of the drawings, the chamber 56 is con nected to atmosphere through the port 35 and the spring 66 holds the valve 50 in the position shown in Fig. 5 of the drawings. In this position of the valve the two pressure chambers within the cylinder are in communication through the port 12, groove 13 and passages 14 and 68. When the valve 33 is actuated to close the port 35 and connect the pressure chamber 56 to the pressure conduit 32 the valve 56 is forced by the air pressure from the position shown in Fig. 5 to the position shown in Fig. 6 where pressure from the conduit 32 is delivered to the main pressure chamber of the cylinder through the chamber 51, passages 60, 63 and 64 and the port 65, and the auxiliary pressure chamber of the cylinder is connected to the atmosphere through the passages 68 and and the port H. The air under pressure in the main pressure chamber then forces the cylinder downwardly toward the lower cross member 29, the impact of the cylinder head 23 against the piston rod being cushioned by the engagement of the plunger 46 in the recess 49 in the head 23. This actuation of the cylinder actuates the trip operating cable [2 to exert a pull upon the lever l4 and latch releasing cable H.

In the operation of the device the valve 33 is momentarily shifted to the position shown in dotted lines in Fig. 4 and then returned to full line position where pressure is released from the chamber 56. Immediately upon the release of pressure in the chamber 56 the spring 66 returns the valve 50 to the position shown in Fig. 5, disconnecting the main pressure chamber from the pressure conduit 32 and closing the passage from the auxiliary chamber to the atmosphere. At the same time the main pressure chamber is connected to the auxiliary pressure chamber through the port 12 and passage 68 so that the air under pressure trapped in the main pressure chamber is allowed to fiow into the auxiliary pressure chamber.

By reason of the fact that the major portion of the space between the piston and the lower head is occupied by the piston rod 22, the piston has a relatively small area exposed to the pressure in the main pressure chamber, and since the main pressure chamber is of relatively small capacity, only a small volume of air under pressure is required to impart the trip operating stroke to the cylinder. The auxiliary pressure chamber, however, is of relatively large capacity and the piston has a relatively large area exposed to the pressure in the auxiliary chamber. When communication is established between the main and auxiliary chambers after the trip operating stroke, the pressure in the two chambers is equalized and because of the fact that the piston face exposed to the pressure in the auxiliary chamber has a much greater area than the piston face exposed to the pressure in the main pressure chamber, the pressure on the upper face of the piston exceeds that on the lower face and the cylinder is returned to its uppermost position to reset the trip mechanism.

Immediately upon actuation of the valve 50 by pressure admitted to its chamber 56 through the valve 33, the pressure trapped in the auxiliary .pre'ssure' chamber of the cylinder (8 is released through the outlet port H so that it does not oppose pressure admitted to the main chamber upon actuation of the valve 50. The operation of the trip mechanism is very rapid since the operating stroke requires only the delivery of the small volume of compressed air to the main pressure chamber required to fill the same and retract the cylinder and the return movement of the cylinder is effected immediately by the: air originally delivered to the main chamber.

In Figs. 9 to 12 of the drawings, a modified. form of trip operating mechanism is shown. In this modification the cylinder is stationary and. the piston and piston rod are movable, a cylinder 15 being provided with an integral base 16 that is adapted to be bolted to a fixed support such as the boom 5. The cylinder 15 has an upper head I1 through which a piston rod I8 extends, the piston rod having an upper end 19 adapted to be attached to a trip actuating cable such as the cable l2. The piston rod 18 has a piston attached thereto within the cylinder 15 and the lower end of the piston rod 18 has a reduced extension 8! of cylindrical form that fits in a cushioning chamber 82 formed in the lower head 83 of the cylinder. Air trapped in the chamber 82 by the plunger extension 8| provides a yielding cushion for cushioning the impact of the piston rod against the head 83. A valve casing 84 which extends parallel with the cylinder 15 is attached to the top of the cylinder 15 by means of attaching bolts 85. The valve casing 84 has a longitudinal bore 86 parallel with the cylinder 15 and has counterbores 81 and 88 at the opposite ends thereof. The ends of the valve casing are closed by means of heads 99 and 90 and a valve 9| is slidably mounted in the bore 86 of the valve casing.

The valve 9! has a slightly enlarged head 92 that forms a piston sliding in the counterbore 88 on the valve casing, the outer end of the counterbore providing a pressure chamber through which air under pressure may be admitted to actuate the valve, a pipe 3 la being connected to the valve casing adjacent the head 90 to conduct air under pressure from a pressure conduit such as shown in Fig. 4 to the valve operating cylinder. To permit the piston 92 to be freely operated by pressure admitted through the pipe 3 la, a vent opening 93 is provided to the counterbore 88 adjacent its inher end. A spring 94 is interposed between the valve 9| and the head 89, the spring 94 serving to normally hold the valve 9| in the position shown in Fig. 10.

The trip mechanism shown in Figs. 9 to 12 may be controlled in the same way as in the modification first described, the valve casing being connected to a pressure conduit such as the pressure conduit 32 through a pipe 3la corresponding to the pipe 3| and through a pipe 39a corresponding to the pipe 39 shown in Fig. 4, a valve such as shown in Fig. 4 being employed to control operation of the valve 9|.

The pipe 36a delivers into a wide circumferential channel 95 formed in the valve 9|, the channel 95 being adapted to register with a port 96 in the valve casing when the valve 9| i shifted in opposition to the spring 94. The port 98 communicates with a longitudinal passage 91 formed in the space between the cylinder 15 and the valve casing 84 which delivers into the space between the piston 88 and the head 11 of the cylinder. A port 98 in the valve casing registers with a circumferential groove 99 in the valve:

1,9I when the valve. 9| is in its normal position in the valvecasing and is connected through the groove 99 with a port I which connects with .a

passage IOI extending longitudinally of the casing that communicates with the interior of the cylinder adjacent the head 83. The valve 9| has a circumferential groove I02 between the channel 95 and the head 92 that is adapted to connect ports I03 and I04 that lead :to the passage NH and to the atmosphere, so that when the valve 9| is shifted by air pressure acting upon the head 92, the auxiliary chamber below the piston 80 will be connected to the atmosphere through the passage IOI, port I03, groove I02 and port I04.

The operation of the trip device shown in Figs. 9 to 12 is essentially like the operation of the modification previously described. When the valve BI is actuated by air under pressure delivered through the pipe 3Ia, the main pressure chamber between the piston 80 and the head 11 receives air under pressure from the pipe 3011 through the channel 95, the port 96 and the passage 91 and the auxiliary pressure chamber'being connected to atmosphere through the passage IOI, port I93, groove I02 and port I04. The air pressure acting upon the piston 80 imparts a downward stroke to the piston rod 82 operating the trip mechanism. Upon return of the control valve to its normal position pressure on the head 92 is released and the valve is immediately returned to normal position by the spring 84, breakin the connection between the auxiliary chamber and the atmosphere and between the main pressure chamber and the pressure conduit. At the same time communication is established between the main and auxiliary pressure chambers through passages 91 and NH that are connected through ports 98 and I00 and valve groove 99. As in the modification first described, the main pressure chamber is of relatively small capacity and the piston has a relatively small area exposed to the pressure of said chamber and the auxiliary chamber has a relatively large capacity and the piston a face of large area exposed to the pressure of the auxiliary chamber. When the pressure in the two chambers is equalized the piston is moved to the upper end of the cylinder by the pressure in the auxiliar chamber because of the fact that the piston area exposed to pressure in the auxiliary chamber greatly exceeds the piston area exposed to the same pressure in the main chamber. The trip mechanism is thus automatically reset after each actuation.

It is to be understood that variations and modifications of the specific devices herein shown and described for purposes of illustration, may be made without departing from the spirit of the invention.

What I claim is:

1. A pneumatic trip actuating mechanism comprising a movable trip member, a fixed support, a piston rod attached to the fixed support, a piston attached to said rod, a cylinder connected to said trip member, said cylinder being slidable upon said piston and having a main pressure chamber surrounding said rod on one side of the piston and an auxiliary pressure chamber on the opposite side of the piston, a presconnect said pressure chambers from the pressure conduit and atmosphere and connect the main pressure chamber to the auxiliary pressure chamber.

2. A pneumatic trip actuating mechanism comprising a movable trip member, a fixed support, :a piston rod connected at one end to said support, a piston attached to said rod, a cylinder connected to said trip member and slidable on said piston, said cylinder having a main pressure chamber surrounding said rod on one side of the piston and an auxiliary pressure chamber on the opposite side of the piston, a valve chamber and a pressure chamber within said rod, said valve chamber having passages to each of said chambers of the cylinder and to the atmosphere, a pressure conduit connected to said valve chamber and to said pressure chamber in said rod, a valve slidable in said valve chamber and having a head portion slidable in the pressur chamber of the rod, said valve having portions controlling the passages to the pressure chambers of the cylinder and being movable from a position disconnecting the main pressure chamber from the pressure conduit and the auxiliary chamber from the atmosphere and connecting the pressure chambers through the valve .chamber, to a position connecting the auxiliary chamber to the atmosphere and disconnecting it from the main chamber and connecting the main chamber to the pressure conduit, and means for operating said valve including a manually operable valve for connecting and disconnecting the pressure chamber in the rod with said pressure conduit.

BERLIN S. FERGUSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 433,822 Robb Aug. 5, 1890 635,848 Dutton Oct. 31. 1899 937,384 Osmer Oct. 19, 1909 1,613,904 Woller Jan. 11, 1927 1,641,131 Baker Aug. 30, 1927 1,937,244 Pelton Nov. 28, 1933 2,171,568 Johnson Sept. 5, 1939 2,365,471 Ingres Dec. 19, 1944 2,379,628 Eberhard July 3, 1945 2,413,287 Bush Dec. 31, 1946 FOREIGN PATENTS Number Country Date 412,756 Great Britain July 5, 1934 644,689 Germany June 14, 1937 

